CA1159327A - Unit fuel injector assembly - Google Patents
Unit fuel injector assemblyInfo
- Publication number
- CA1159327A CA1159327A CA000386814A CA386814A CA1159327A CA 1159327 A CA1159327 A CA 1159327A CA 000386814 A CA000386814 A CA 000386814A CA 386814 A CA386814 A CA 386814A CA 1159327 A CA1159327 A CA 1159327A
- Authority
- CA
- Canada
- Prior art keywords
- fuel
- plunger
- pressure
- stroke
- injector
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
ABSTRACT
A unit fuel injector assembly that integrates into a single unit a fuel injector, a plunger type pump, an electromagnetic actuator for the pump, and a mechanical stroke control for varying the output of the pump as a function of the fuel injector fuel return line pressure.
A unit fuel injector assembly that integrates into a single unit a fuel injector, a plunger type pump, an electromagnetic actuator for the pump, and a mechanical stroke control for varying the output of the pump as a function of the fuel injector fuel return line pressure.
Description
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UNIT FUEL INJECTOP~ ASSEMBLY
This invention relates in general to an automotlve type fuel injectlon system and controls. Although it has universal application to all fuel injection systems, it is 5 particularly suitable for torch type ign~tion systems in which a minute amount of fuel is injected into a precombustion chamber and ignited with precise timiny to form a small pilot flame that ignites the leaner main charge in the main combustion chamber. The fuel injection system in particular 10 includes a set of unit injector assemblies that comprise afuel injector integrated with a plunger type fuel pump, a solenoid actuator, and a mechanical stroke control mechanism for varying the volume of fuel pumped. The stroke control mechanism is variably movable in response to chanyes in the 15 return fuel pressure, i.e~, of the fuel vented or returned to the fuel supply system inlet.
Fuel injection systems of this general type in the prior art fail to provide the compact, electrica~ly energlzed unit injector assemblies of the type of this invention. For 20 example, U.S. 3,990,413, Pischinger, shows a plunger type pumping assembly with a delivery valve and a stroke control for varying the plunger stroke; however, these elements are not integrated into a single unit, there is no electromagnetic means ~or actuating the plunger, nor is the stroke control 25 operated by the pressure level of the return fuel.
U.S. 3,6~5,192 shows a fuel injection system in which fuel is pressurized behind a metering plunger 12 to determine the length of time the plunger remains open. However, the ~roke control is not controlled by fuel pre~sure and the 30 plun~r 12 operates mor~ like a needle valve ~han a pumping plunger~
U.S. 3,837,324, Links, shows an inteyrated ~uel injection assembly baving a pump and nozzle a~sembly integrated, ~nd ~olenoid means ~or controlling a ~uel valva~
33 However, the stroke control mechanism is not varied by varying fluid return pressure.
U.S~ 4,044,745, Brinkman, shows an oscillating pump '~
~ ~5~3~
arld an electromagnet, with stroke control means, but not constructed in the manner of this invention. The pump has an entirely different activating mechanism and the stroke control is not ~aried by return fuel pressure.
In accordance with the present invention, there is provided a unit fuel pumping and metering assembly con-sisting o~ a fuel injector, a plunger type fuel pump, an electromagnetic actuator for the plunger pump, and plunger stroke control means all integrated into a single compact unit ~or controlling the amount and duration of injection of ~uel ~rom the injector, the injector being of the spring closPd, fuel pressure opened type having a fuel inlet containing a one-way check valve and connected to a source of supply fuel at a low pressure, the inlet being below one end of a plunger movable to one position through a fuel intake stroke by the fuel under pressure from the inlet acting thereagainst, the plunger and armature of a solenoid surrounding the plunger being integrated for unitary movement, energization of the solenoid by electrical impulses thereto e~fecting a movement of the plunger in the opposite direction through a pumping stroke to increase the fuel pressure to a level effecting a closing of the check ~alve and an opening of the ~uel injector and an expulsion of the fuel therefrom, the stroke control means including mechanical stop means variably movable into the plunger through its intake stroke to thereby vary the volume o~ fuel inducted to thereby vary the amount of ~uel injected during each movement of the plunger through its pumping stroke, and a fluid pressure actuated device to vary the intake stroke of the plunger as a function of the change in pressure of the actuating fluid, a fuel return flow line for collecting fuel leaking ~rom the assembly, means to maintain a minimum pressure level to -the return ~uel ~low and to vary khe level above khe minimum, and means to apply the retuxn uel ~low to the ~luid pressure 3S actuaked dqvice to ackuate khe stroke control as a func~ion o~ khe return ~uel pressure level.
O~he.r ~eaku.res and advantages o~ the invenkion will become more apparent upon re~erence to the succeedin~
de~ailed description thereo~, and to the drawings illustrating .~0 the pre~erred embodiments thereo.~; wherein:
, ,i . . ' ` ~. , ': ~
~ls~3~æ~7 Figure 1 schematically illustrates a fuel injecticn and control system embodying the invention;
Figure 2 is an enlarged cross-sectional view of one of the unit fuel injectors shown in Figure l;
Figure 3 is a cross-sectional view taken on a plane indicated by and viewed in the direction of the arrows III-III
of Figure 2;
:, . : ~ . . , ,. -3~fZ7 Figure 4 is an enlarged cross-sectional view of t~e pressure regulator mechanism shown in Figure l; and Figures 5 and 6 are schematic block diagram representations of controls for various elements of the system shown in Figure 1 to control operation of the same.
The fuel injection system shown in Figure l includes a main fuel supply pump 10 that draws fuel from a tank or reservoir 12 and delivers the same at a low pressure into a fuel supply llne 14. Supply line 14 has three branches 16, 18 and 20. The line 16 supplies fuel continuously through four sub-branch lines 22 to four unit fuel injector assemblies 24.
As will be described later, and as seen in Figures 2 and 3, each of the unit injector assemblies 24 includes a fuel injector, a plunger type pumping unit, a solenoid for actuating the plunger, and a stroke control means actuated by the level of the fuel pressure in a return line 26 connected to each of the unit injector assemblies, as shown.
- The fuel supply branch line 20 is, as indicated, adapted to be connected to the main fuel injection pump of the system to supply fuel continuously thereto in an a~ount in excess of that required by the pump. As stated previously, this fuel injection system is particularly suitable for a prechamber type engine construction for supplying a small controlled amount of fuel to the prechamber through the unit injector assemblies 24.
Fuel supply branch line 18 is shown as connected to the inlet 28 of a first fixed level pressure regulator 30.
The purpose o~ this regulator 30 is to assure an adequate and c~nstant supply fuel pressure to the unit injectors that is always high~r than the fuel pressure in the return lines 26.
In this case, the pressure regulator 30 consists of a casing 32 partitioned by an annular flexible diap~ragm 34 into an atmo~pheric pres~ure chamber 36 and a ~uel pre~sure chamber 3~. A sprin~ 40 normally biase~ a disc-~ype valve 42 towards the end o~ a stand pipe 44 to throt~le communication of Euel Erom branch supply line 18 to a discharger line 46 connected ~L~L5~3~
to the fuel return lines 26. An adjustable screw mechanism 48 is provided for fixing the preload on spring 40 to thereby set the pressure in supply line 28 at a constant valve equal to the force of the spring 40. Any higher pressure will move the disc valve 42 leftwardly to uncover stand pipe 44 more and vent more of the fuel into return line 46 until the set pressure level is regained.
Each of the return lines 26 from the lnjector unit assemblies 24 is connected to the inlet 50 of a second variable pressure regulator unit 52 shown more clearly in Figure 4. This particular pressure regulator is controlled by a solenoid coil energizable in accordance with changing engine operating conditions. More particularly, pressure regulator 52 consists essentially of a three-piece assembly that includes a fuel chamber defining housing 54, the stationary core 56 of a solenoid assembly, and the moveable combination armature-valve mechanism 58 of the solenoid.
Hollow housing 54 is bolted to the annular stationary core 56 of the solenoid with the edges of an annular flexible diaphragm 60 secured therebetween. The housing contains an opening through which is inserted a stand pipe 62 constituting a fuel outlet that is adapted to be connected to tank 12 shown in Figure 1 to return fuel thereto leaking past the elements of the unit fuel injector assemblies 24 and vented from the pressure regulator device 30. The stationary core 56 in this case is secured to a solenoid coil 64 that surrounds the core and the moveable armature 58. An adjustable screw mechanism 66 is provided for adjusting the conventional gap 68 between the moveable and stationary parts of the solenoid, in a known manner. A valve element or piston 70 is shown screwed to the armature 58 of the solenoid through a hole in the annular di~phragm 60~ Suitable wiring 72 (Figure 1) connects the solenold co~l 64 to a senso~ uni~ 74 operably selectively connected to various parts o~ the ln~ernal combustion engine on which the injection system is installed.
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In this case, the unit 74 could be a microprocessor unit receiving signals from various portions of the engine with respect to temperature, speed, pressure, etc. for converting the same into an electrical impulse signal that is then fed to the solenoid coil 64 at the desired time. This voltage signal will cause the armature 58 to move rightwardly towards the end of the stand pipe 62 to throttle the communication of return fuel from the inlet 50 through standpipe 62. When the pressure of the fuel return acting on diaphragm 60 equals the force of the armature pushing the valve element 70 in the opposite direction, then an equ~librium position will be obtained and the fuel pressure in line 50 will remain at that level. The pressure force will always be equal to the magnetic force of the solenoid, and since the magnetic force is a function of the current in the solenoid coil, varying the voltage applied to the solenoid coil will, therefore, vary the pressure of the return fuel upstream of the pressure regulator unit 52. As will be understood shortly, varying the fuel return pressure will vary the stroke of the pumping plungers of the unit fuel injector assemblies 24.
More specifically, Figures 2 and 3 show the construction of the unit injector assemblies 24. The lower part of each assembly 24 contains a conventional fuel injector 80 having a fuel pressure actuated valve that opens outwardly when the ~uel pressure reaches a sufficient level. The details of construction of this particular injector are not given since they are known and believed to be unnecessary for an understanding of the invention. Suffice it to say that it could be constructed as fully shown and described in U.S.
3,542,293, Bishop et al assigned to the assignee of this inv~ntion, with a tension spring unit Eoc maintaining the valve clo~ed below a predetermined ~uel pressure.
Fuel injector 32 at it~ upper end contains a fuel inlet a4 that is connected to the ~uel pressu~e branch supply line 22 shown in Figure 1~ Although not shown, a check valve ,, ::, would be ~ncluded in the line to permit entry of fuel into inlet 84 but closure of the inlet upon actuation of the pump plunger unit to be described to prevent the return of fuel out of the supply line.
The unit ~njector 80 is inserted into the lower open end of a second housing 86 that encloses a solenoid coil 88 secured to an annular stationary coee element 90. The latter surrounds a reciprocable armature element 92 that is formed integral with a plunger 94 to constitute a fuel pumping unit.
The upper end of the pump plunger 94 is, as seen in Figure 3, of a forked shape to provide a yoke 96 that receives therein the cylindrical portion of a stroke control rod 98. The plunger-armature 92 also is formed with a flange lO0 that constitutes a seat for a spring 102 that lightly biases the plunger-armature upwardly into engagement with the bottom surface o~ control rod 98.
The control rod 98 in this case determines the stroke of the plunger 92 and therefore controls the volume of fuel injected through the unit injector 80 at any particular time.
The control rod 98 is slideably movable essentially at right angles to the axis of plunger 72, and moves in a housing 104.
It is tapered longitudinally, as shown, providing a conical surface 99. The control rod is moveable axially to vary the point of engagement with the Pork or yoke 96 of the pump plunger to thereby vary the distance the plunger can travel upwardly on its fuel intake stroke.
The leftward (as seen in Figure 2) end of control rod 98 is ~ixed to an annular flexible diaphragm 106 by means of a pair of nut like members 108. The diaphragm partitions a hous~ng cap 110 into an atmospheric air chamber 112 and a fuel pcessuce chamber 114/ Chambec 112 is connected to atmosphece th~ough a v~nt hole 116, while chamber 114 i~ connected to the ~uel ln the pump plunger housing thcough a poct 118 connected to the upper chamber 120 containing ~uel leaklny between the armature and the ~tationary coce o~ the solenoid. ~he Euel in chamber 120 passes out to a drain or return llne 26 through an annulus 122 connected to an axial passage 124 ln the control . ., ~.
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rod 98 open at its end to the return passage. Opposite ends of the control rod are formed with hex-head sockets 126 and 128 for insertion o-E a Allen-head type wrench to adjust the axial position of the control rod relative to the nut like retaining members 108. The purpose of this is to permit initial calibration of all unit injector assemblies for identical fuel delivery of the same reference return fuel pressure level. It will be clear that a change in the pressure level of the return fuel in line 26 will be reflected against the right side of the diaphragm 106 to oppose the force of the atmospheric pressure in chamber 112 and the force of a spring 127 biasing the control rod 98 to the right, to vary the position of the control rod with reference to the fork or yoke 96 of the pump plunger. Accordingly, the travel lS distance during the intake stroke of plunger 94 will be varied, thereby controlling the amount of fuel intake and controlling the volume of fuel ultimately injected during the pumping stroke.
While not shown, the solenoid coil 88 would be connected electrically to the engine microprocessor or other suitable control element 74 for energization at the desired time to move the pump plunger or armature 94 downwardly to pressurize the fuel in the unit injector 80. The fuel fills the injector volume underneath the plunger 94 and, therefore, is compressed during downward movement of the plunger to a level above the opening pressure level of the in~ector, whereby the volume of fuel desired is injected into the engine combustion chamber proper. The timing of the injection will be controlled by the timing of the solenoid pulses as a function of engine speed, load and other parameters. The amount o~ fuel injected, as stated previously, is determined by ~he plunger stroke, which can be varied by varying the upp~r starting position o~ the plunger 94 while its lower position ~top remalns ~ixed.
From the above description, it will be seen that the unit injector assembly o~ the inven~ion provides a preci~e control o~ the injection o~ a small quantity o-F ~uel over a Lri~
predetermined period, which is quite suitable as the fuel supply for a prechamber type combustion chamber. Of course, a system similar to the one described can also be used for control of the fuel to the ma~n combustion chamber. The basic difference in this particular case would be the larger amounts of fuel that are needed for a main combustion chamber and a greater accuracy of fuel delivery control to assure the proper air to fuel ratio control. The larger amounts of fuel injected can be handled by increasing the diameter and the stroke of the plunger 94, and the use of a more powerful solenoid. The accuracy of this system can be improved by using a closed loop control electronic system, as compared with an open loop system normally used for the system already described.
More particularly, Figures 5 and 6 illustrate examples of open and closed loop control systemsl respectively. Figure 5 is a block diagram of the open loop control system for specific use with a torch ignit~on or prechamber type engine construction. Figure 1 illustrates the fuel supply branch line 20 as being connected to a main fuel injection pump that supplies fuel to the main combustion chamber. This pump could be as fully shown and described in U.S. 4,197,059, Simko, assigned to the assignee of this invention. It shows a fuel pump flow control lever 180 whose rotational position indicates the quantity of ~uel flowing ~rom the pump. ~he block diagram of Figure 5 in this application indicates an input from the pump control sha~t of the main fuel injection pump (such as is shown in Simko) connected to a position sensor that develops a controlling voltage signal representing the control shaft angle, which is then converted into a Euel pressure signal by the solenoid controlled pressure regulator S2 shown in Figure 1 to thereby con~rol the level o~ the return Euel pressure signal in line 26 connected to each o~ the ~uel inj~ction unit assemblies 24.
Figure 6 shows a block diagram o~ the closed loop control system that could be used ~or controlling the injection o~ Euel into a main combustion chamber type o~
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construction. In this case, the angle of the throttle valve located in the air induction pipe leading to the engine combustion chamber is sensed by the position sensor indicated, which converts the same into a voltage signal that, in thls case, could be modified in accordance with the speed and temperature of the engine, for example, to produce a signal that is shaped for proper relationship of the torque and throttle angle. The resulting feedforward voltage sagnal represents the required schedule of the fuel pressure signal in return line 26 that controls the fuel delivery stroke in all unit injector assemblies 24. In this case, a pressure sensor is installed in the return fuel line to generate a feedback voltage signal that is compared to the feedforward voltage signal, as indicated. The resulting error signal is then added to the feedforward signal, modifying it into a controlling voltage signal applied to the terminals of the solenoid pressure regulator 52. So long as the pressure signal corresponds to the required schedule, the feedback and feedforward voltage signals would be equal, and the error 2Q signal zero; the controlling voltage signal, therefore, is equal to the feedfoward signal. Any deviation from the required value of the pressure signal would then produce a positive or negative error signal which would modify the controlling voltage signal to minimize the deviation.
The operation is ~elieved to be clear from the above description and a consideration of the drawings and therefore will not be given in detail. Suffice it to say that the supply pump 10 always supplies an excess of fuel through the system and through the pressure regulator valve unit 30 so as to provide a return fuel flow in line 46 and in the return lines 26 to the pressure regulator unit 52. The unit injector as~emblies are ~illed with Euel supplied through the inlet 84 a~ a low pressure levql. Energization oE the solenoid 88 causes the plunger 9~ to move downwardly ~o compre~s the Euel in the lnjector 80 and open the same to inject fuel ou~ into the engine proper. The stroke or volume oE ~uel injected is determJned by the axial position oE the control rod 98 to vary L~327 the location of the conical surface of the rod with respect to the fork or yoke ~6 to limit the upper or intake stroke of the plunger. The variance of the return fuel pressure in line 26 will determine the position of the control rod and will, therefore, determine the volume of fuel injected. In turn, the signal from the microprocessor unit 74 to the solenoid controlled pressure regulator 52 will vary the backpressure or return pressure in line 26 to thereby vary the stroke control in accordance with the demand of the engine.
While the invention has been shown and described in its preferred embodiments, it will be clear to those skilled in the arts to which it pertains that many changes and modifications may be made thereto without departing from the scope of the invention.
i.;, ,. . . .
UNIT FUEL INJECTOP~ ASSEMBLY
This invention relates in general to an automotlve type fuel injectlon system and controls. Although it has universal application to all fuel injection systems, it is 5 particularly suitable for torch type ign~tion systems in which a minute amount of fuel is injected into a precombustion chamber and ignited with precise timiny to form a small pilot flame that ignites the leaner main charge in the main combustion chamber. The fuel injection system in particular 10 includes a set of unit injector assemblies that comprise afuel injector integrated with a plunger type fuel pump, a solenoid actuator, and a mechanical stroke control mechanism for varying the volume of fuel pumped. The stroke control mechanism is variably movable in response to chanyes in the 15 return fuel pressure, i.e~, of the fuel vented or returned to the fuel supply system inlet.
Fuel injection systems of this general type in the prior art fail to provide the compact, electrica~ly energlzed unit injector assemblies of the type of this invention. For 20 example, U.S. 3,990,413, Pischinger, shows a plunger type pumping assembly with a delivery valve and a stroke control for varying the plunger stroke; however, these elements are not integrated into a single unit, there is no electromagnetic means ~or actuating the plunger, nor is the stroke control 25 operated by the pressure level of the return fuel.
U.S. 3,6~5,192 shows a fuel injection system in which fuel is pressurized behind a metering plunger 12 to determine the length of time the plunger remains open. However, the ~roke control is not controlled by fuel pre~sure and the 30 plun~r 12 operates mor~ like a needle valve ~han a pumping plunger~
U.S. 3,837,324, Links, shows an inteyrated ~uel injection assembly baving a pump and nozzle a~sembly integrated, ~nd ~olenoid means ~or controlling a ~uel valva~
33 However, the stroke control mechanism is not varied by varying fluid return pressure.
U.S~ 4,044,745, Brinkman, shows an oscillating pump '~
~ ~5~3~
arld an electromagnet, with stroke control means, but not constructed in the manner of this invention. The pump has an entirely different activating mechanism and the stroke control is not ~aried by return fuel pressure.
In accordance with the present invention, there is provided a unit fuel pumping and metering assembly con-sisting o~ a fuel injector, a plunger type fuel pump, an electromagnetic actuator for the plunger pump, and plunger stroke control means all integrated into a single compact unit ~or controlling the amount and duration of injection of ~uel ~rom the injector, the injector being of the spring closPd, fuel pressure opened type having a fuel inlet containing a one-way check valve and connected to a source of supply fuel at a low pressure, the inlet being below one end of a plunger movable to one position through a fuel intake stroke by the fuel under pressure from the inlet acting thereagainst, the plunger and armature of a solenoid surrounding the plunger being integrated for unitary movement, energization of the solenoid by electrical impulses thereto e~fecting a movement of the plunger in the opposite direction through a pumping stroke to increase the fuel pressure to a level effecting a closing of the check ~alve and an opening of the ~uel injector and an expulsion of the fuel therefrom, the stroke control means including mechanical stop means variably movable into the plunger through its intake stroke to thereby vary the volume o~ fuel inducted to thereby vary the amount of ~uel injected during each movement of the plunger through its pumping stroke, and a fluid pressure actuated device to vary the intake stroke of the plunger as a function of the change in pressure of the actuating fluid, a fuel return flow line for collecting fuel leaking ~rom the assembly, means to maintain a minimum pressure level to -the return ~uel ~low and to vary khe level above khe minimum, and means to apply the retuxn uel ~low to the ~luid pressure 3S actuaked dqvice to ackuate khe stroke control as a func~ion o~ khe return ~uel pressure level.
O~he.r ~eaku.res and advantages o~ the invenkion will become more apparent upon re~erence to the succeedin~
de~ailed description thereo~, and to the drawings illustrating .~0 the pre~erred embodiments thereo.~; wherein:
, ,i . . ' ` ~. , ': ~
~ls~3~æ~7 Figure 1 schematically illustrates a fuel injecticn and control system embodying the invention;
Figure 2 is an enlarged cross-sectional view of one of the unit fuel injectors shown in Figure l;
Figure 3 is a cross-sectional view taken on a plane indicated by and viewed in the direction of the arrows III-III
of Figure 2;
:, . : ~ . . , ,. -3~fZ7 Figure 4 is an enlarged cross-sectional view of t~e pressure regulator mechanism shown in Figure l; and Figures 5 and 6 are schematic block diagram representations of controls for various elements of the system shown in Figure 1 to control operation of the same.
The fuel injection system shown in Figure l includes a main fuel supply pump 10 that draws fuel from a tank or reservoir 12 and delivers the same at a low pressure into a fuel supply llne 14. Supply line 14 has three branches 16, 18 and 20. The line 16 supplies fuel continuously through four sub-branch lines 22 to four unit fuel injector assemblies 24.
As will be described later, and as seen in Figures 2 and 3, each of the unit injector assemblies 24 includes a fuel injector, a plunger type pumping unit, a solenoid for actuating the plunger, and a stroke control means actuated by the level of the fuel pressure in a return line 26 connected to each of the unit injector assemblies, as shown.
- The fuel supply branch line 20 is, as indicated, adapted to be connected to the main fuel injection pump of the system to supply fuel continuously thereto in an a~ount in excess of that required by the pump. As stated previously, this fuel injection system is particularly suitable for a prechamber type engine construction for supplying a small controlled amount of fuel to the prechamber through the unit injector assemblies 24.
Fuel supply branch line 18 is shown as connected to the inlet 28 of a first fixed level pressure regulator 30.
The purpose o~ this regulator 30 is to assure an adequate and c~nstant supply fuel pressure to the unit injectors that is always high~r than the fuel pressure in the return lines 26.
In this case, the pressure regulator 30 consists of a casing 32 partitioned by an annular flexible diap~ragm 34 into an atmo~pheric pres~ure chamber 36 and a ~uel pre~sure chamber 3~. A sprin~ 40 normally biase~ a disc-~ype valve 42 towards the end o~ a stand pipe 44 to throt~le communication of Euel Erom branch supply line 18 to a discharger line 46 connected ~L~L5~3~
to the fuel return lines 26. An adjustable screw mechanism 48 is provided for fixing the preload on spring 40 to thereby set the pressure in supply line 28 at a constant valve equal to the force of the spring 40. Any higher pressure will move the disc valve 42 leftwardly to uncover stand pipe 44 more and vent more of the fuel into return line 46 until the set pressure level is regained.
Each of the return lines 26 from the lnjector unit assemblies 24 is connected to the inlet 50 of a second variable pressure regulator unit 52 shown more clearly in Figure 4. This particular pressure regulator is controlled by a solenoid coil energizable in accordance with changing engine operating conditions. More particularly, pressure regulator 52 consists essentially of a three-piece assembly that includes a fuel chamber defining housing 54, the stationary core 56 of a solenoid assembly, and the moveable combination armature-valve mechanism 58 of the solenoid.
Hollow housing 54 is bolted to the annular stationary core 56 of the solenoid with the edges of an annular flexible diaphragm 60 secured therebetween. The housing contains an opening through which is inserted a stand pipe 62 constituting a fuel outlet that is adapted to be connected to tank 12 shown in Figure 1 to return fuel thereto leaking past the elements of the unit fuel injector assemblies 24 and vented from the pressure regulator device 30. The stationary core 56 in this case is secured to a solenoid coil 64 that surrounds the core and the moveable armature 58. An adjustable screw mechanism 66 is provided for adjusting the conventional gap 68 between the moveable and stationary parts of the solenoid, in a known manner. A valve element or piston 70 is shown screwed to the armature 58 of the solenoid through a hole in the annular di~phragm 60~ Suitable wiring 72 (Figure 1) connects the solenold co~l 64 to a senso~ uni~ 74 operably selectively connected to various parts o~ the ln~ernal combustion engine on which the injection system is installed.
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In this case, the unit 74 could be a microprocessor unit receiving signals from various portions of the engine with respect to temperature, speed, pressure, etc. for converting the same into an electrical impulse signal that is then fed to the solenoid coil 64 at the desired time. This voltage signal will cause the armature 58 to move rightwardly towards the end of the stand pipe 62 to throttle the communication of return fuel from the inlet 50 through standpipe 62. When the pressure of the fuel return acting on diaphragm 60 equals the force of the armature pushing the valve element 70 in the opposite direction, then an equ~librium position will be obtained and the fuel pressure in line 50 will remain at that level. The pressure force will always be equal to the magnetic force of the solenoid, and since the magnetic force is a function of the current in the solenoid coil, varying the voltage applied to the solenoid coil will, therefore, vary the pressure of the return fuel upstream of the pressure regulator unit 52. As will be understood shortly, varying the fuel return pressure will vary the stroke of the pumping plungers of the unit fuel injector assemblies 24.
More specifically, Figures 2 and 3 show the construction of the unit injector assemblies 24. The lower part of each assembly 24 contains a conventional fuel injector 80 having a fuel pressure actuated valve that opens outwardly when the ~uel pressure reaches a sufficient level. The details of construction of this particular injector are not given since they are known and believed to be unnecessary for an understanding of the invention. Suffice it to say that it could be constructed as fully shown and described in U.S.
3,542,293, Bishop et al assigned to the assignee of this inv~ntion, with a tension spring unit Eoc maintaining the valve clo~ed below a predetermined ~uel pressure.
Fuel injector 32 at it~ upper end contains a fuel inlet a4 that is connected to the ~uel pressu~e branch supply line 22 shown in Figure 1~ Although not shown, a check valve ,, ::, would be ~ncluded in the line to permit entry of fuel into inlet 84 but closure of the inlet upon actuation of the pump plunger unit to be described to prevent the return of fuel out of the supply line.
The unit ~njector 80 is inserted into the lower open end of a second housing 86 that encloses a solenoid coil 88 secured to an annular stationary coee element 90. The latter surrounds a reciprocable armature element 92 that is formed integral with a plunger 94 to constitute a fuel pumping unit.
The upper end of the pump plunger 94 is, as seen in Figure 3, of a forked shape to provide a yoke 96 that receives therein the cylindrical portion of a stroke control rod 98. The plunger-armature 92 also is formed with a flange lO0 that constitutes a seat for a spring 102 that lightly biases the plunger-armature upwardly into engagement with the bottom surface o~ control rod 98.
The control rod 98 in this case determines the stroke of the plunger 92 and therefore controls the volume of fuel injected through the unit injector 80 at any particular time.
The control rod 98 is slideably movable essentially at right angles to the axis of plunger 72, and moves in a housing 104.
It is tapered longitudinally, as shown, providing a conical surface 99. The control rod is moveable axially to vary the point of engagement with the Pork or yoke 96 of the pump plunger to thereby vary the distance the plunger can travel upwardly on its fuel intake stroke.
The leftward (as seen in Figure 2) end of control rod 98 is ~ixed to an annular flexible diaphragm 106 by means of a pair of nut like members 108. The diaphragm partitions a hous~ng cap 110 into an atmospheric air chamber 112 and a fuel pcessuce chamber 114/ Chambec 112 is connected to atmosphece th~ough a v~nt hole 116, while chamber 114 i~ connected to the ~uel ln the pump plunger housing thcough a poct 118 connected to the upper chamber 120 containing ~uel leaklny between the armature and the ~tationary coce o~ the solenoid. ~he Euel in chamber 120 passes out to a drain or return llne 26 through an annulus 122 connected to an axial passage 124 ln the control . ., ~.
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rod 98 open at its end to the return passage. Opposite ends of the control rod are formed with hex-head sockets 126 and 128 for insertion o-E a Allen-head type wrench to adjust the axial position of the control rod relative to the nut like retaining members 108. The purpose of this is to permit initial calibration of all unit injector assemblies for identical fuel delivery of the same reference return fuel pressure level. It will be clear that a change in the pressure level of the return fuel in line 26 will be reflected against the right side of the diaphragm 106 to oppose the force of the atmospheric pressure in chamber 112 and the force of a spring 127 biasing the control rod 98 to the right, to vary the position of the control rod with reference to the fork or yoke 96 of the pump plunger. Accordingly, the travel lS distance during the intake stroke of plunger 94 will be varied, thereby controlling the amount of fuel intake and controlling the volume of fuel ultimately injected during the pumping stroke.
While not shown, the solenoid coil 88 would be connected electrically to the engine microprocessor or other suitable control element 74 for energization at the desired time to move the pump plunger or armature 94 downwardly to pressurize the fuel in the unit injector 80. The fuel fills the injector volume underneath the plunger 94 and, therefore, is compressed during downward movement of the plunger to a level above the opening pressure level of the in~ector, whereby the volume of fuel desired is injected into the engine combustion chamber proper. The timing of the injection will be controlled by the timing of the solenoid pulses as a function of engine speed, load and other parameters. The amount o~ fuel injected, as stated previously, is determined by ~he plunger stroke, which can be varied by varying the upp~r starting position o~ the plunger 94 while its lower position ~top remalns ~ixed.
From the above description, it will be seen that the unit injector assembly o~ the inven~ion provides a preci~e control o~ the injection o~ a small quantity o-F ~uel over a Lri~
predetermined period, which is quite suitable as the fuel supply for a prechamber type combustion chamber. Of course, a system similar to the one described can also be used for control of the fuel to the ma~n combustion chamber. The basic difference in this particular case would be the larger amounts of fuel that are needed for a main combustion chamber and a greater accuracy of fuel delivery control to assure the proper air to fuel ratio control. The larger amounts of fuel injected can be handled by increasing the diameter and the stroke of the plunger 94, and the use of a more powerful solenoid. The accuracy of this system can be improved by using a closed loop control electronic system, as compared with an open loop system normally used for the system already described.
More particularly, Figures 5 and 6 illustrate examples of open and closed loop control systemsl respectively. Figure 5 is a block diagram of the open loop control system for specific use with a torch ignit~on or prechamber type engine construction. Figure 1 illustrates the fuel supply branch line 20 as being connected to a main fuel injection pump that supplies fuel to the main combustion chamber. This pump could be as fully shown and described in U.S. 4,197,059, Simko, assigned to the assignee of this invention. It shows a fuel pump flow control lever 180 whose rotational position indicates the quantity of ~uel flowing ~rom the pump. ~he block diagram of Figure 5 in this application indicates an input from the pump control sha~t of the main fuel injection pump (such as is shown in Simko) connected to a position sensor that develops a controlling voltage signal representing the control shaft angle, which is then converted into a Euel pressure signal by the solenoid controlled pressure regulator S2 shown in Figure 1 to thereby con~rol the level o~ the return Euel pressure signal in line 26 connected to each o~ the ~uel inj~ction unit assemblies 24.
Figure 6 shows a block diagram o~ the closed loop control system that could be used ~or controlling the injection o~ Euel into a main combustion chamber type o~
' ' 3~.~
construction. In this case, the angle of the throttle valve located in the air induction pipe leading to the engine combustion chamber is sensed by the position sensor indicated, which converts the same into a voltage signal that, in thls case, could be modified in accordance with the speed and temperature of the engine, for example, to produce a signal that is shaped for proper relationship of the torque and throttle angle. The resulting feedforward voltage sagnal represents the required schedule of the fuel pressure signal in return line 26 that controls the fuel delivery stroke in all unit injector assemblies 24. In this case, a pressure sensor is installed in the return fuel line to generate a feedback voltage signal that is compared to the feedforward voltage signal, as indicated. The resulting error signal is then added to the feedforward signal, modifying it into a controlling voltage signal applied to the terminals of the solenoid pressure regulator 52. So long as the pressure signal corresponds to the required schedule, the feedback and feedforward voltage signals would be equal, and the error 2Q signal zero; the controlling voltage signal, therefore, is equal to the feedfoward signal. Any deviation from the required value of the pressure signal would then produce a positive or negative error signal which would modify the controlling voltage signal to minimize the deviation.
The operation is ~elieved to be clear from the above description and a consideration of the drawings and therefore will not be given in detail. Suffice it to say that the supply pump 10 always supplies an excess of fuel through the system and through the pressure regulator valve unit 30 so as to provide a return fuel flow in line 46 and in the return lines 26 to the pressure regulator unit 52. The unit injector as~emblies are ~illed with Euel supplied through the inlet 84 a~ a low pressure levql. Energization oE the solenoid 88 causes the plunger 9~ to move downwardly ~o compre~s the Euel in the lnjector 80 and open the same to inject fuel ou~ into the engine proper. The stroke or volume oE ~uel injected is determJned by the axial position oE the control rod 98 to vary L~327 the location of the conical surface of the rod with respect to the fork or yoke ~6 to limit the upper or intake stroke of the plunger. The variance of the return fuel pressure in line 26 will determine the position of the control rod and will, therefore, determine the volume of fuel injected. In turn, the signal from the microprocessor unit 74 to the solenoid controlled pressure regulator 52 will vary the backpressure or return pressure in line 26 to thereby vary the stroke control in accordance with the demand of the engine.
While the invention has been shown and described in its preferred embodiments, it will be clear to those skilled in the arts to which it pertains that many changes and modifications may be made thereto without departing from the scope of the invention.
i.;, ,. . . .
Claims (2)
1. A unit fuel pumping and metering assembly con-sisting of a fuel injector, a plunger type fuel pump, an electromagnetic actuator for the plunger pump, and plunger stroke control means all integrated into a single compact unit for controlling the amount and duration of injection of fuel from the injector, the injector being of the spring closed, fuel pressure opened type having a fuel inlet containing a one-way check valve and connected to a source of supply fuel at a low pressure, the inlet being below one end of a plunger movable to one position through a fuel intake stroke by the fuel under pressure from the inlet acting thereagainst, the plunger and armature of a solenoid surrounding the plunger being integrated for unitary movement, energization of the solenoid by electrical impulses thereto effecting a movement of the plunger in the opposite direction through a pumping stroke to increase the fuel pressure to a level effecting a closing of the check valve and an opening of the fuel injector and an expulsion of the fuel therefrom the stroke control means including mechanical stop means variably movable into the plunger through its intake stroke to thereby vary the volume of fuel inducted to thereby vary the amount of fuel injected during each movement of the plunger through its pumping stroke, and a fluid pressure actuated device to vary the intake stroke of the plunger as a function of the change in pressure of the actuating fluid, a fuel return flow line for collecting fuel leaking from the assembly, means to maintain a minimum pressure level to the return fuel flow and to vary the level above the minimum, and means to apply the return fuel flow to the fluid pressure actuated device to actuate the stroke control as a function of the return fuel pressure level.
2. The unit assembly of Claim 1, wherein the plunger is located on the longitudinal axis of the injector in an end-to-end relationship, the stroke control means includes a control rod extending essentially transversely to the axis of the plunger into the path of movement of the plunger to be engaged thereby, the rod has a conical surface tapering along a portion of its length and being movable laterally of the plunger by the fluid pressure device, and spring means bias the plunger against the control rod to define the limit of the plunger intake stroke varying as a function of the lateral movement of the rod.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US19398380A | 1980-10-06 | 1980-10-06 | |
| US193,983 | 1980-10-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1159327A true CA1159327A (en) | 1983-12-27 |
Family
ID=22715856
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000386814A Expired CA1159327A (en) | 1980-10-06 | 1981-09-28 | Unit fuel injector assembly |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS5791369A (en) |
| CA (1) | CA1159327A (en) |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5118010A (en) * | 1974-08-05 | 1976-02-13 | Toho Denki Kogyo Kk | Atc sochikirokukyoekisukauntokairo |
| DE2805785A1 (en) * | 1978-02-11 | 1979-08-16 | Bosch Gmbh Robert | HIGH PRESSURE FUEL INJECTION DEVICE FOR COMBUSTION MACHINES |
| JPS5532903A (en) * | 1978-07-31 | 1980-03-07 | Riken Corp | Sintering alloy material for internal combustion engine valve seat and its preparation |
-
1981
- 1981-09-28 CA CA000386814A patent/CA1159327A/en not_active Expired
- 1981-10-05 JP JP56158560A patent/JPS5791369A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5791369A (en) | 1982-06-07 |
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| MKEX | Expiry |